In this kind of apparatus there had been hitherto known a so-called trailing type apparatus in which a pair of left and right trailing arms connected to a pair of left and right wheels are provided on the lower surface of a vehicle body frame at a pair of laterally extending left and right rotary shafts at their base ends so as to be individually swingable, and it has been usual in this case for each of the rotary shafts to be supported by bearings at both its inner and outer end portions. Accordingly, there are unavoidable disadvantages in that there are four bearing points in total, that is, two points for each of the left and right sides and thus the apparatus beocmes complicated in construction and large in weight.